How to tell if a Thompson is really full auto or not

Need to know as I have never seen a FA one that I know of. Here's the story. I know a guy who has a Thompson and he SAYS it is FA. I never asked if he had the appropriate legal paperwork for it if it is but he probably does since he is an up and up guy. Anyway, I might go to his house this weekend and will ask to see it again, what do I look for to see if it is really a FA Tommy Gun?

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earlthegoat2

June 4, 2010, 11:54 AM

As a general rule, if it fires from the open bolt then it is full auto.

I believe if you cock the bolt on an empty chamber with no mag in the gun it should stay back and this is how you know it fires from the open bolt.

kanook

June 4, 2010, 12:11 PM

Short barrel
and a
Selector switch

earlthegoat2

June 4, 2010, 12:26 PM

Selector switch

That too. Just like this

Sniper X

June 4, 2010, 06:45 PM

Awesome...thanks.

Madcap_Magician

June 7, 2010, 12:03 PM

Heh heh heh, I was gonna say, the big clue to me would be a selector switch that says "AUTO."

desidog

June 16, 2010, 12:10 PM

The F/A's fire from open bolt; many had a fixed nub on the bolt as a firing pin - no separate moving part.

The semi's fire from closed bolt, with a firing pin.

Anothermiller

June 24, 2010, 09:53 PM

Also, if you look at the right side, opposite the side where the 2 seperate levers are(safe & fire) and (auto & semi), you'll see 3 leaf holding the pins in- shaped like a backwards "E".Semis only use 2, like a sideways "U"

These are located just above the trigger guard,on the lower receiver.

Carl N. Brown

June 24, 2010, 11:21 PM

Most modern (post-1973) semi-auto Thompsons sold as M1927 or as TM1 have a 16.5 inch barrel, fire from a closed bolt, and have only a safety switch. Semi-auto Thompson short barrel rifle (SBR) has a 10.5 inch barrel same as the submachinegun, but no selector switch.

The full-auto Thompsons were made with a 10.5 inch barrel, fire from open bolt position, and have a seperate semi- and full-auto switch between the safety switch and the magazine catch.

And the full-autos are marked on the side of the receiver Thompson Sumachine Gun. Except the original 1927 M1927 Semiautomatic Carbine which had the Submachine Gun stamp ground out and restamped. However, the original 1927 M1927 Semiautomatic Carbine was just a M1921 Submachinegun with the selector dummied out, and most police depts that bought them had the fire control groups later swapped out, making them same as a 1921 in function.

AK103K

June 25, 2010, 08:54 AM

The easiest way to tell with an open bolt gun is, with the gun empty of course, pull the bolt back to cock, and while holding the bolt knob, pull the trigger and hold it to the rear, allow the bolt to go forward, and cycle it a few times without stopping. If its a full auto, the bolt will continue to cycle. If its not, it will stop on the first trip back.

Thats assuming its selector, if there is a selector, is set to full. If its set on semi, it will work like a normal semi auto gun. This will also work with closed bolt guns, but wont be as obvious.

If its cool and you get to fire it, make sure you get a good walk through on what to do and expect from the gun. Open bolt guns can be a little tricky if youre not used to them, and have a slightly different manual of arms than the closed bolt guns.